The term millwork refers to formed building construction members that are often rabbeted. Doorjambs, trim pieces and window frame components are representative of millwork.
A doorjamb, for example, which is a structure for receiving a door when closed, typically consists of three members, two vertical "legs" and one horizontal "head" which connects the upper ends of the legs. These doorjamb members have been commonly fabricated from lumber by cutting a single piece to yield the desired rabbeted shape.
When fabricating doorjamb members and the like from lumber, problems result the non-uniformity of the material, e.g., the presence of irregularities such as mixed grains, wood texture variations, moisture content differences, splits and/or knots. Shaping the lumber to achieve the desired configuration can be costly and results in a significant waste of material. Moreover, the cost of lumber of suitable quality has increased substantially in recent years.
To improve the relatively low fire rating of lumber, which is a measure of its ability to withstand a specified temperature for a specified time period, conventional wooden doorjamb members are sometimes given a fire retardant coating or impregnation. Laminated film and paint print coatings or veneers are sometimes applied for decorative purposes. The application of a veneer can be done manually in longitudinal sections, but requires additional fabrication expense, and produces interfaces where delamination could occur later.
Other such members have been formed from aluminum, by an extrusion process, or from steel. However, metal doorjambs are generally more expensive. For aesthetic or decorative reasons and to prevent oxidation, they have been often painted or otherwise covered in a decorative manner, requiring an additional step and higher labor costs in their fabrication. Steel members are difficult to install requiring tools and skill that often are not readily available at the construction site.
A principal objective of the present invention is to provide doorjamb members and other millwork building construction members that are made of relatively inexpensive materials. A further objective is to retain the advantages of conventionally constructed members and providing new solutions to some problems associated with previously known members of this type. A still further objective is to provide an improved method for the fabrication of such members.